To play Windows Media in Firefox, you need the Windows Media Player browser plugin installed. There are two different versions:

The original, which is usually included with Windows up until XP.

The new version, specifically developed for Windows XP and above, which is only available by download.

This article describes how to check for and install the Windows Media Player Firefox plugin. Many Windows XP users will have the old plugin but it is recommended that you install the new plugin, anyway.

Even if you have Windows Media Player installed, you may still be missing the plugin required to play back Windows Media audio and video content in web pages.

Mplayer is a popular Linux media player that can play back Windows Media files. In order to use Mplayer to play a Windows Media stream in Firefox, you must install two packages, named gnome-mplayer and gecko-mediaplayer. Your Linux distribution may have these packages readily available to install.

Microsoft discontinued the Macintosh version of Windows Media Player in 2006. The Flip4Mac replacement added Windows Media playback capabilities to QuickTime and was distributed for free until May 1, 2014, when Telestream began charging for Flip4Mac Player. For more information, see this Telestream article.

If you want a free player for many different media types, including Windows Media, you can try the VLC Media Player for Mac OS X. To play embedded audio and video content on web pages, you would need to download the VLC Web Browser plugin package (available from the Download VLC drop-down menu). For other alternatives, try the Mac App Store.

If you want to disable the plugin, select Never Activate in its drop-down menu.

If you want to re-enable the plugin, select Always Activate in its drop-down menu.

If the plugin is disabled, pages with embedded Windows Media such as the "Windows Media test" linked above will not work and, if you download a Windows Media file, Firefox may ask you what to do with the file instead of automatically opening it in Firefox.

Links to media files

The Windows Media formats handled by the plugin include asf, asx, wm, wma, wax, wmp, wmv, and wvx. When you click on a link to download a Windows Media file and the plugin is enabled, it will open automatically in Firefox using the plugin. If you do not want this to happen, you can select a different download action in your Firefox Application settings for Windows Media files. For more information, see Change what Firefox does when you click on or download a file.